Both currently and in the past, when a vehicle body having been subjected to electrodeposition coating is baked inside a drying furnace, a coating fluid of electrodeposition paint gushes or flows out, in particular, from a gap of a steel sheet laminated portion of a door sash portion and a steel sheet laminated portion of a lower end of a sac-shaped portion of a door, so that there is a problem in that the coating fluid sags down and is cured at an upper surface, a side surface, and the like of a side sill of the vehicle body (hereinafter, referred to as a sagging defect of electrodeposition paint). When this sagging defect of electrodeposition paint occurs, there is a need to grind off a cured portion formed by the coating fluid dropped thereto so that the portion is smoothened together with an electrodeposition coating cured surface of the side sill.
However, since it takes some time for the work of grinding off the portion with the sagging, a problem arises in that waste materials generated by the grinding adhere to the vehicle body again.
For this problem, according to Patent Document 1 below, there is proposed a technology in which a heater and a shower device are provided in a transfer path for transferring a vehicle body having been subjected to electrodeposition coating to a drying furnace. The heater uses hot air to locally heat a surface of a vehicle body, such as a roof, a filler portion, or a locker portion having a small gap opening into which a coating fluid of electrodeposition paint may intrude, so as to boil the coating fluid. Accordingly, the fluidity of the coating fluid intruding into the gap increases and the coating fluid thermally expands, whereby the intruding coating fluid flows out from the gap. Subsequently, the coating fluid flowing out therefrom is cleaned and removed by shower water of the shower device.